Re: [PATCH 5/6] meta/dpkg: add dpkg-custom class

[Henning Schild <henning.schild@siemens.com>]

Am Mon, 4 Sep 2017 18:36:23 +0300
schrieb Alexander Smirnov <asmirnov@ilbers.de>:

> On 08/30/2017 10:03 PM, Henning Schild wrote:
> > Issues:
> > 1. full customizations of the images is hard to impossible to
> > realize in a layer without touching Isar
> > 1.1. there is no easy way to just copy a file into the image
> > 1.2. configuration (passwords, groups, cfg-files changes) can not be
> > done in a layer, there is no way too hook into multistrap or the
> > configure-script
> > 
> > Change:
> > Introduce a class that lets users create custom debian packages on
> > the fly, without having to create a /debian directory and actually
> > building. That allows you to pull in debian-dependencies, you could
> > have a package that has no content and is just there to install
> > what you need for a feature of your product.
> > Using package hooks (preinst, postinst ..) you can configure pretty
> > much all you want when installing the package.
> > The package can contain actual payload as well, basically any files
> > that come from "somewhere else". Say binary data like wallpapers,
> > sound files or application binaries.
> > 
> > Impact:
> > This patch addresses the metioned issue in a way that uses debian
> > mechanism. All the customizations will enjoy features like
> > - collission protection (multiple packages providing the same file)
> > - config file protection
> > - versioning and the ability to deploy your changes in an
> > updateable way
> > 
> > This patch introduces a major new feature to Isar.
> > 
> > This class introduces a new class for building debian packages on
> > the fly. They can basically contain anything from random sources,
> > where building happens outside of Isar. It also allows to create
> > meta-packages that contain nothing but pull in dependencies, once
> > all our packets come in via multistrap that will come in handy.
> > For rootfs configuration you would use post- and pre- scripts just
> > like regular debian packages do.
> >   
> 
> Good idea.
> 
> > Signed-off-by: Henning Schild <henning.schild@siemens.com>
> > ---
> >   meta/classes/dpkg-custom.bbclass | 57
> > ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 57
> > insertions(+) create mode 100644 meta/classes/dpkg-custom.bbclass
> > 
> > diff --git a/meta/classes/dpkg-custom.bbclass
> > b/meta/classes/dpkg-custom.bbclass new file mode 100644
> > index 0000000..e4e743f
> > --- /dev/null
> > +++ b/meta/classes/dpkg-custom.bbclass
> > @@ -0,0 +1,57 @@
> > +# This software is a part of ISAR.
> > +# Copyright (C) 2017 Siemens AG
> > +
> > +inherit dpkg
> > +
> > +DEBIAN_DEPENDS ?= ""
> > +MAINTAINER ?= "FIXME Unknown maintainer"
> > +
> > +D = "${WORKDIR}/image/"
> > +
> > +# Populate folder that will be picked up as package
> > +# TODO this should be called 'do_install'
> > +do_populate_package() {
> > +	bbnote "Put your files for this package in ${D}"
> > +}
> > +
> > +addtask populate_package after do_unpack before
> > do_deb_package_prepare +
> > +# so we can put hooks etc. in there already
> > +do_populate_package[dirs] = "${D}/DEBIAN"
> > +
> > +do_deb_package_prepare() {
> > +	cat<<-__EOF__ > ${D}/DEBIAN/control
> > +		Package: ${PN}
> > +		Architecture: `dpkg --print-architecture`
> > +		Section: misc
> > +		Priority: optional
> > +		Maintainer: ${MAINTAINER}
> > +		Depends: `echo ${DEBIAN_DEPENDS} | tr '[:blank:]'
> > ','`
> > +		Version: ${PV}+isar
> > +		Description: ${DESCRIPTION}
> > +	__EOF__
> > +	for t in pre post
> > +	do
> > +		for a in inst rm
> > +		do
> > +			chmod -f +x ${D}/DEBIAN/${t}${a} || true
> > +		done
> > +	done
> > +}
> > +
> > +addtask deb_package_prepare after do_populate_package before
> > do_deb_package_conffiles +
> > +do_deb_package_conffiles() {
> > +	CONFFILES=${D}/DEBIAN/conffiles
> > +	find ${D} -type f -path '*/etc/*' | sed -e 's|^${D}|/|' >>
> > $CONFFILES
> > +	test -s $CONFFILES || rm $CONFFILES
> > +}
> > +
> > +addtask deb_package_conffiles after do_deb_package_prepare before
> > do_deb_package +
> > +do_deb_package() {
> > +	sudo chown -R root:root ${D}/DEBIAN/
> > +	sudo dpkg-deb --build ${D} ${WORKDIR}
> > +}
> > +
> > +addtask deb_package after do_deb_package_conffiles before
> > do_install 
> 
> If I got this correctly, the difference from dpkg-debian flow is that 
> you generate 'debian' folder on the fly. So:

Well it is a capital "DEBIAN" folder that contains the package metadata
and no build instructions like 'debian'.

> 1. Why we need another do_deb_package, while do_build from dpkg class 
> does the same?

do_build does not do the same. It eventually calls 'dpkg-buildpackage'
which does "configure; make; make install; make deb"

Using the same language this step is just "make deb" and it uses the
debian tool 'dpkg-deb'.

Custom steps for "configure; make;" could be added in the future. "make
install" is do_populate_package.

> 2. Can we just add optional task to generic pipeline which generates 
> debian folder? Or make it as a part of do_build: if [ ! -d
> ${D}/debian ]; then blablabla.

That would be adding support for 'debian'-izing a source package.

This patch is more about packaging binaries and creating meta-packages.

Henning